The invention relates to an apparatus for the multistage biological purification of waste water, particularly for the degradation of carbohydrate and protein-containing industrial waste water.
Highly polluted waste water is very effectively purified through a combination of anaerobic and aerobic degradation. Such processes are well known. The waste water is first treated in an anaerobic stage in order to produce methane and is subsequently treated aerobically in an activated sludge process to cause oxidation and flocculation of the sewage by bacterial action. The sewage then settles and yields a harmless effluent.
This combination of anaerobic and aerobic treatment can attain a 99.9% reduction in the biochemical demand of waste water.
The conventional processes are satisfactory for purifying but have the disadvantage of requiring a large number of both large and small apparatuses and containers as well as suitable conduits between them. Also, the separation of the activated sludge in the aerated tank is difficult; separation can only be achieved by the addition of a settling tank to the treatment facility. It now appears that special compact integral parts can be built for small and intermediate installations; these compact parts are relatively simple to operate and, with appropriate waste water flow, require less expense. This is what the present invention relates to.